Power transmitting device with resilient shock absorbing means



Oct. 26, 1954 BER-[SCH ETAL 2,692,661

POWER TRANSMITTING DEVICE WITH RESILIENT SHOCK ABSORBING MEANS Filed May 27, 1952 2 Sheets-Sheet l I INVENTORS jass x Ban-5c 650265 lMJfiCKSO/Y 41%,Mk a.

file/2 ATTORNEYS.

Patented Oct. 26, 1954 POWER TRANSMITTING DEVICE WITH RE- SILIENT SHOCK ABSORBING MEANS Joseph F. Bertsch and George W. Jackson, Dayton, Ohio, assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application May 27, 1952, Serial No. 290,288

11 Claims.

This invention relates to a power driven actuator and shock absorbing mechanism.

It is among the objects of the present invention to provide a power driven actuator to be connected between two relatively movable bodies for adjusting the relative position of said bodies, the actuator being adapted to resist and cushion any undesirable movements between said bodies for the purpose of preventing damage to the mechamsm.

A further object of the invention is to provide an actuator as aforedescribed with shock absorbing mechanism which not only cushions movements of the bodies between which it is connected, but also returns the mechanism to its originally adjusted position after the forces, causing the undesirable movements, are discontinued.

The actuator of the present invention may most advantageously be used on a military tank where it is anchored to the breech end of a pivotally mounted gun or cannon and to an immovable portion of the tank, the actuator being operated by a power device such as an hydraulic motor, for moving the gun about its trunnion for elevating or lowering the ordnance during aiming thereof. While the tank is being operated over smooth terrain, the actuator is subjected to comparatively small stress or strain. However, in many instances the tank must pass over large obstructions or humps and suddenly dip into deep ditches or ruts which cause the comparatively long and heavy gun to whip thereby subjecting the actuator to strains and stresses which damage an actuator built surllciently large and sturdy to actuate the gun as desired but still too small to withstand the excessive stresses caused by gun whip.

The present invention provides the actuator with shock absorbing and cushioning means which relieves the actuating mechanism of the device from the excessive strains and by frictional means dissipates the ordinarily damaging thrusts exerted upon the device by the whipping action of the ordnance. This frictional means is contained within the actuator itself and under normal conditions remains inactive and is not affected by stresses set up within the actuator while it is being operated to raise or lower the end of the ordnance to which it is attached. During gun-whip this frictional means is active to cushion the thrusts upon the actuator. However, as soon as the whipping action of the gun ceases then said means assumes its normal centering position, that is, the position holding the gun in its last adjusted or aimed position.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. l is a fragmentary, schematic view showing the actuator attached to the breech end of a tank ordnance.

Fig. 2 is a longitudinal sectional view of the actuator-shock absorbing device.

Fig. 3 is a fragmentary sectional view taken substantially along the line and in the direction of the arrows 3-3 of Fig. 4.

Fig. 4 is a transverse sectional view taken along the line and in the direction of the arrows 44 in Fig. 2.

Fig. 5 is a detail view, partly in section taken along the line and in the direction of the arrows 5-5 in Fig. 4.

Referring to the drawings, the actuator is shown consisting of a composite housing made up of a main body portion 2!! provided with a cap 2| and an end ring 22 to which a tube 23 is secured preferably by welding. Another end cap 24 is welded to the outer end of tube 23 and is centrally apertured to house a sealed bearing 25. These various parts of the composite housing are secured together in any suitable manner preferably by bolts 26. The end cap 2| has a ring portion 30 which is attachable to any suitable member whose movement is to be effected by the actuator. In the installation shown a flange 3! is provided on the breech end 32 of a cannon or ordnance supported pivotally at 33 upon the body portion 34 of a military tank.

The housing portion 29 supports the power de vice 35 which may be of any desirable type, as for instance a hydraulic motor actuated by hydraulic pressure so as to rotate its drive shaft 36, shown in Fig. 4. Roller bearings 37, supported within the housing 20 and also by a portion of the end cap 2|, rotatably support the power transmitting or driver tube 33 which has a work gear 39 provided about its outer peripheral surface adjacent the ball bearings 37 which support said tube. Tube 38 extends through the tubular member 23, terminating short of the end cap 24 attached to tube 23. .An inner annular recess in tube 38 extends from the outer end of the tube and forms the annular shoulder 455 adjacent the area at which the worm gear portion 39 is formed on said tube. From the shoulder 48 to the end of tube 38 supported by ball bearings 3? the inner peripheral wall of the tube is provided with splines forming keyways for cooperating with exterior splines formed on the inner power transmitting tube 4! which telescopically fits within the outer power transmitting tube 38. This inner tube 5i extends telescopically through the outer tube 38-and into a recess in the end cap 24 in which recess'there is provided a roller bearing 42 rotatably supporting this inner end of the tube 4|. Tube 41 has an annular recess provided in its outer peripheral wall which recess extends from theend of the tube supported by roller bearing 42 to an annular shoulder [33 formed on tube M and substantially in the same plane as the annular shoulder formed in the tube 38. The-inner recess in tube 38 and the outer annular recess on tube 4! form an annular space or chamber betweensaid two tubes for purposes to be described. The outer end of this annular chamber, that is, adjacent the end cap 2 1 is substantially closed by collars 45 ands lfi the first being:threadedlyrsecured in theend of tubular member 38;.the other :mem

ber collar '46 being securedito'the :tubular meme: her 4!, said collarhaving anintegral locking flange 4T whichis bent into a'recesssin the outer.

wall of the tube 4! so as to lock said collar :48 against. accidental movement on: the tube 51-.

From the aforegoing it may be seen :that the interfitting and cooperating spline .portionsof the I tubes 38 and operatively 'connectsaid tubes so that rotation of tube- 38Uwi'1l. cause rotation of the tube 4! therewith and'at the same time permit tubeiil 'to move'longitudinally'of :the tube 38. Tube 38 can not move longitudinally in'the housing due-tothe abutment. ringnfi being secured to the 'end of tube' 38 and :engaging the ball. bearing 31 to retain it in position withinnthe the outer peripheral surface of the screw 52, the

spiral grooves on said tube 4! and the screw 52 together forming a spiral channel in which a' plurality of balls 53 circulate, said balls threadedly connecting the screw 52 with the inner tube 4!. Screw 52 is attached to one end of the drivenmember or shaft 55 which slidably extends through the sealing bearing 25 in the end cap 24 to the exterior of the device and has the mounting ring 55 secured thereto, said mounting ring 56 being attachable to one or the other of the two relatively movable members, in'the present instance the body portion 34 of the tank. The shaft or driven member 55 is secured to the bracket 5'4, rendering said shaft 55 nonrotatable and thus the screw 52 attached to the shaft will also be nonrotatable. Therefore rotation of the inner tubular driving member 4! will cause the screw 52 to be reciprocated longitudinally of the tube 4! being threadedly connected to said, tube. Reciprocation of the screw 52 in one direction or the other, dependent upon the direction of rotation of the tube i 1 will cause the entire housing of the device to be moved longitudinally of the stationary shaft 55 "and thus in this installation will move the breech end of the gun 32 relatively to the immovable bracket 5! to which the actuator is anchored, thereby raising or lowering the barrel of the gun or ordnance as it is moved about its pivotal support 33.

As has previously been stated the outer tube 38, or what may be termed the outer power transmitting tube 38, is rotatably driven by a power device 35, in this instance a hydraulic motor, said power device having a stub drive shaft 36.

The hydraulic motor 35 i mounted upon a tubular extension 5: of liousing.2ll.- In this-tubular extension a roller bearing 52 'and'a .ball bearing 63 are provided, which rotatably support the cylindrical member '34 which has worm gear teeth 65 on its outer periphery operatively engaged by the worm 39 .onthe driver tube 38. A collar is carried inside the cylindrical member 5a and iskeyed'thereto by ,pin 5? so as to rotate therewith; The inner .end edge of this collar has an annular row of teeth providing a face gear ing 'theiace gear 62; A transverse opening in:

shaft "1e carries ballbearings in. which the stub shaft 74' is journaled, said stubishaft having gear teeth at its one end which'operativelyengagethe face gears 68 and:lsiat' alltimes The-end of collar- :12 opposite the face gear'ls 'end'thereof is oval in cross-sectional shape as shown in Fig; 2, thereby forminga cam for purposes to'be'described;

Thehub of a disc 65 iskeyedto the stub drive Disc 55 has two diametrically opposh'aft' Sfi: sitesegment shaped flanges andiifiiextend-l ing from-one side thereof, said flanges envelop.-

ing the cam'zshaped'end portion of collar '72 as' shown in Fig. This 'disc rotates withina nonrotata'ble 'cylindricalshel'lfl whichis. an integral extensiomof the body of motor. 35;; The. camend of"colla'r :72 :fiextending inter-the shell]? forms two crescent-"shapedi hambers .on opposite sides of the cam separateduby the two segmental flanges- 75 and '15 on disc 68.

against: the respective segmental- =fianges .by a spring 82 interposed between said rollers. Rollers 83 anduB i'; in the opposite crescent shaped. chamb'eware urged against'theopposite edges of therespective segmental fianges-i5and 'ISby spring'85 interposed between rollers iZB-and 84.

These segmental flanges l5 and Won-the disc fiil'each'h'ave a'wideportio'nas shown in section in Fig. 2 and in elevationin Fig; 5, from the outer end edges of which extends a narrow-protuberance 86 which in turn extends into a groove-:81 I

in the peripheral surface'of the collar'12, said groove being wider than the protuberance extending into'said groove. This provides a lost motion but still positive-driving connection between the disc 60' and the collar 12.

Shaft 10 has a collar'90 keyed'to it, said collar 90being'oval-shaped, the same-as collar 72, to form a cam. A disc 9 I 'on'shaft 92 has segmental flanges 93 and 94 extending therefrom and embracing-the cam-'collar90. Like'the segmental flanges 15=and 16of disc'60,"flanges 93 and 94 each-havea wide'portion and a narrower pro tuberance 95 which extends in a'groove in collar 95, said groove being "somewhat wider than the by providing a drivinguconnection betweenthe disc 9| and collar'90,said connection having a.

Each crescent Shaped chamber contains two .clutch'i 1'01161517, Rollers 80 and '8! inthe one chamber are urged.

lost motion. Clutch rollers, not shown, but similar to the rollers 8034 with cam collar 12 are provided with cam collar 90, said rollers being associated with springs 96 and 91, shown in Fig. 5. The shaft 92 is connectible with any suitable manually operable means by which the actuator may manually be operated in case of failure of the hydraulic motor 35.

When the ordnance 32 is to be raised or lowered by moving it about its pivotal support 33 for aiming purposes, the hydraulic motor is rendered active to operate the power transmitter. As the motor 35 rotates in one direction it will turn the disc 60 in the same direction so that the segmental flanges 75 and 13 will be rotated. If for instance the rotation is clockwise as regards Fig. 2, flange 15 will push clutch roll 80 out of gripping engagement with the cam collar l2 and surrounding sleeve H and flange 16 will do the same to roll 84. However, spring 82 will urge roll 8| into gripping engagement with the cam collar and sleeve and spring 85 will do the same to roll 03 inasmuch as flanges l5 and 73 are now rotating away from the respective rolls 33 and 0|. Now cam collar 12 will be rotated with disc 60 and the face gear 73 on said collar 12 will endeavor to carry with it the gear stub shaft '54 meshing with said face gear. Stub shaft 14 is radially supported by shaft which is keyed to the cam collar 90. When shaft 10 tries to turn the cam collar 90, the clutch mechanism between the cam collar 90 and the disc flanges 33 and 94 will lock the shaft against rotation inasmuch as this clutch mechanism is now working just the opposite to the clutch mechanism including rollers 3084 associated with cam 12. With shaft 10 locked against rotation, stub shaft 16 may only rotate about its own axis and thus the face gear 13 on cam collar 72 will rotate shaft 14 and it in turn will rotate the face gear 63 provided on collar 58 which is pinned to the cylindrical member 64. Now collar 58 and member 34 will be rotated and consequently the driver tube 30 will also be rotated due to the worm gear 3055 connection. When tube 38 rotates, the tube 4| will also be rotated and consequently screw 52 and its attached shaft 55 will be reciprocated to extend or retract the entire device whereby the ordnance will be actuated about its pivot 33 in one direction or the other dependent upon the direction of rotation of the power transmitting device by the motor 35.

In case of fai ure of the hydraulic motor 35, the mechanism is manually operative by turning shaft 92. When this shaft is manually rotated the disc 3| and its segmental flanges 93 and 94 are rotated. The clutch mechanism associated with disc 9| now acts in the same manner as the clutch mechanism at the motor end of the device with the motor providing the power. The clutch mechanism will grasp the cam collar 90 so that it turns with the disc 9| and thus rotates the shaft 10 keyed to collar 30. As shaft 10 r0- tates, the radial stub shaft 14 carried by shaft l0 will be revolved about the axis of shaft '10. The clutch mechanism associated with cam collar 12 will hold said collar against rotation by the revolving stub shaft 14 geared to said collar 12 and thus, due to the geared connection of stub shaft 14 with face gear 68, the stub shaft will be rotated about its own axis and turn said face gear 38 and its collar 65. Through its pin connection 61, collar 56 will turn the cylindrical member 64 and through the worm-gear connection, the driver tube 30 will be rotated to effect reciprocation of the nut and shaft as before.

As has been previously described, longitudinal annular recesses in the two tube power transmitting tubes 38 and 4| form an annular chamber bound by the annular walls of the recesses in said tubes and at the ends by shoulders 40 and 43 at one end and by the collars 45 and 43 secured respective to the tubes 33 and 4 I. Within the annular space there are located a plurality of inner and outer rings I00 and |0|. Each ring is separate, rings I00 fitting loosely about the sleeve 4| so as to provide clearance therebetween the end rings respectively engaging the shoulder 43 and the collar 46. The outer rings 0| fit loosely within the sleeve 38 so as to provide clearance therebetween, the end or outer rings respectively engaging the shoulder 40 and the collar 45 attached to said tube 38. Adjacent annular surfaces of the rings I00 and I0! are wedge-shaped that is, the outer peripheral surface of each ring I00 comprises two hip-shaped, sloping surfaces 00L and |00R converging outwardly, the apex being substantially midway between the edges of the ring. The inner annular surface of each ring IN is similarly shaped. Thus, these nested, engaging rings are normally positioned so that a ring of one group has its wedged-shaped surfaces |00L and |00R engaging a corresponding surface of the two opposite rings, thereby normally spacing the rings in each group to provide clearance between adjacent rings in each group. These rings are preferably made of a high grade steel adapted to be expanded and contracted by outwardly and inwardly directed forces applied thereto. When assembled these rings are preloaded by nuts 45 and 46 to a load considerably in excess of that encountered in normal positioning of the gun.

Any thrusts caused by the reciprocation of the screw 52 in the turning sleeve 4| for elevating or lowering the gun have no effect upon the rings I00 and NI inasmuch as these thrusts caused by the raising and lowering of the gun due to actuator operation are not of sufficient value to exceed the assembled preload and effect relative movement between the rings I00 and NH.

As long as the tank upon which the ordnance 32 is mounted, traverses comparatively smooth terrain there are no whipping forces by the gun directed against the actuator. However, when the tank is operated over large obstructions such as humps or stony terrain or driven across deep gullies or ditches, which cause the tank to careen, gun whip, due to the weight and size of the ordnance 32, will result causing excessive forces to be directed against the actuator which is anchored between the gun and the body portion of the tank. Under ordinary circumstances these gun-whip thrusts are sufficiently strong to damage the actuator, especially its screw threaded connection about the screw and driving tube and thrust bearings and therefore the rings Hi0 and 0| are provided to cushion and absorb these thrusts and thereby protect the actuator against damage resulting from these excessive forces. If whip of the gun moves the breech end thereof downwardly, the housing and the shoulder 40 in tube 38, secured to the housing, will exert a downward thrust upon the rings |0| to compress the rings I00 while the rings |0| are expanded as they tend to ride over the rings I00. This opposing movement of the rings I00 and |0|, due to thrust being made against the actuator, will result in a wedging action between engaging rings causing the inner rings I00 to be compressed and the outer rings ml to be expanded.

"The. expansion. resistancebf .these-ringsiis comparatively high and thusthe forces tending to move them relatively will be partially dissipated by the friction actionof the engaging. surfaces of rings 1% and. 101. The deflection allowed by the rings I90 and [ill permits the appliedshock to-be absorbed over a stroke SllfilClel'lt to limit the maximum load to that for which the actuator was designed. As soon as the force or thrust is removed the resiliency of the rings causes them to assume their normal position thereby again returning the actuator tubes 38-and 4! to their normal adjusted, position-which, due to the connection of the actuator with the gun, again cen-- ters or returns the gun to its aimedposition or the position into which it was adjusted prior to the application of the forces due to the gun whip. The friction action of the rings 508 and i8! provides a damping action to preventoscillation of the gun and return it to the sighting position after a minimum number of cycles.

The rings and It! are designed predeter minately to offerthe'required resistance'to the gun. whip. Where smaller guns are used, smaller rings H30 and it! may effect the necessary centering operation while'comparatively larger and heavier ordnance will require rings i136 and till having greater resistance to expansion and. contraction.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A self-centering, shock absorbing power transmitting device consisting ofaJpower rotated driver, a first rotatable andz-reciprocative driven member connected with anddriven by said driver; a second reciprocative. driven mem- 13811111821115 operably connecting said first driven member and said second driven member to reciprccate said second driven member in response to rotation of the first driven member, and resilient means consisting of memberscarried by the driver engaging similar resilient means carried by the first driven member, said engaging resilient means yieldably holding said driver and driven member in relative fixed normal position and resisting, in a cushioning manner, relative movement of said driver and said first driven member in either direction in said one plane.

2. A self-centering, shock absorbing power transmitting device consisting of a reversible power rotated driver, a reciprocative driven member; power translating means connected to the driver to be rotated thereby and to move relatively thereto in the direction of reciprocation of the driven member, said means being operatively connected to the driven member for reciprocating itin response to rotation of said means; and a plurality of resilient rings carried by both the driver and the power translating means, the rings on the driver frictionally engaging the rings on said power translating means, the engaging faces of said rings being wedge-shaped whereby said rings yieldably resist and cushion relative movement between said driver and said power translating means and will return said driver and said means into relative normal position. after each relative movement therebetween.

3. A device connectible between two relatively movable bodies for cushioning movement ofone of said bodies relatively to the other and'for adjusting said one body relatively to the other, said device consistingiof a housing attached to one of saidbodies; a power device. on said housingoperativelyconnected to two driving elementsconnected together for common rotation and relative longitudinal movement; cooperating resilient devices interposed between said driving elements providing predetermined resistance to relative longitudinal movements between said elements and cushioning such movements when saidgpredetermined resistance is overcome; and a driven element reciprocatively supported by the housingand connected to one of the driving elements, said driven element being reciprocatedxbyithe rotation of the connected driving element and being anchored to the other of said bodies.

'4. A device connectible between two relatively movable bodies for cushioning movement ofone of said bodies relatively to the other and foradjusting said one body relatively to the other, said device consisting of a housing attached to one of said bodies; a reversible power device carried by said housing; two power transmitting -elements rotatably supported within said housing, one element being connected to the power. device to be rotated thereby and so connected to the second element to rotate it and to permit longitudinal movement of said second element relatively to said one-element; a plurality of separate inter-engaging relatively movable resilient members interposed between and engaged by said power transmitting elements, said members collectively providing a predetermined resistance to relative longitudinal movement between said elements and cushioning such movements when said resistance is overcome; and a driven element reciprocatively carried by the housing and threadedly connected to the said second power transmitting element to be reciprocated in response to rotation of said second element.

5. A device connectible between two relatively movable bodies for adjusting one of said bodies relatively to the other and for cushioning movement between said bodes, said device consisting of a housing attachable to one of said bodies; a reversible power device supported by said housing; two power transmitting elements within the housing, one operatively connected to the power device to be rotated thereby, the other connected to said one element to rotate therewith and be movable longitudinally thereof; a driven element reciprocatively supported by the housing and threadedly connected to the said other power transmitting element and connected also to the other relatively movable body; and a plurality. of rings carried by each of the power transmitting elements, the outer rings on each element engaging a rigid abutment on the element, the intermediate rings being spaced axially one from. the other and from the end rings on the respective elements, the rings on one element having sloping camming faces constantly engaging similar sloping camming faces of the rings on the other element, said engaging camming faces being-relatively moved one set of rings over the other in response to relative longitudinal movementbetween the two power transmitting elements whereby the rings on one element are compressed and the rings on the other element are expanded resulting in cushioning the relative movement of said elements out of normal position and the return of said elements to their normal position.

6. A device connectible between two. relatively movable bodies for adjusting one of said bodies relatively to the other and for cushioning movement between said bodies, said device consisting of a housing attachable to one of said bodies;a

reversible power device supported by said housing; two power transmitting elements within the housing, one operatively connected to the power device to be rotated thereby, the other connected to said one element to rotate therewith and be movable longitudinally thereof; a driven element reciprocatively supported by the housing and threadedly connected to the said other power transmitting element and connected also to the other relatively movable body; a plurality of separate expandable rings on the one power transmitting element, the two outer rings engaging rigid shoulders provided on said element, the other power transmitting element having a plurality of separate, compressible rings mounted upon it, the two outer rings engaging rigid shoulders provided on said other element, the inner and outer peripheral surfaces of the rings on the one and the other element respectively having converging sloping surfaces presenting hiplike formations whereby a ring on one element nests between and engages two opposed rings on the other element which spaces the separate rings edgewise on each element, the engaging hiplike faces acting as cams for expanding and contracting said rings in response to relative movement between said power transmitting elements whereby said movement is cushioned.

7. A device connectible between two relatively movable bodies and being operative to adjust the position of one body relatively to the other and to resist and dampen undesirable movement between said bodies, the device returning said bodies to their normal relative positions after said undesirable movements cease, said device consisting of a housing connectible to one of said bodies; a reversible power device attached to said housing, a tubular member rotatably supported within the housing and operatively connected to the power device to be rotated thereby; another tubular member telescopically fitting into the first tubular member and keyed thereto to rotate therewith and move longitudinally relatively thereto, portions of both tubes cooperating to form an annular chamber therebetween, a reciprocative member slidably supported by the housing and extending into the said other tubular member with which it is threadedly connected, said reciprocative member being attached to the other of said bodies; and means within said annular chamber operative predeterminately to resist relative longitudinal movement between said tubular members, said means consisting of alternately opposed and engaging camming rings the expansion and contraction of which in response to end thrusts thereupon by relative longitudinal movements of said tubular members predeterminately resists and cushions such movements and returns said members to their normal relative positions.

8. A device connectible between two relatively movable bodies and being operative to adjust the position of one body relatively to the other and to resist and dampen undesirable movement between said bodies, the device returning said bodies to their normal relative position after said undesirable movements cease, said device consisting of a housing connectible to one of said bodies; a reversible power device attached to said housing, a tubular member rotatably supported within the housing and operatively connected to the power device to be rotated thereby; another tubular member telescopically fitting into the first tubular member and keyed thereto to rotate therewith and move longitudinally relatively thereto, the contiguous annular surfaces of said tubular members, not provided with the key connection, being recessed to provide an annular chamber one end of which is substantially closed by adjacent abutment collars attached to the respective tubular members; a shaft slidably extending from the housing and attached to the other relatively movable body, said shai' t extending into the said other tubular member and being threadedly connected thereto so that rotation of said other tubular member causes reciprocation of the shaft relatively to the housing; and a plurality of engaging inner and outer metal rings in said annular chamber, the inner rings having wedge-shaped outer walls and, the outer rings similarly wedge-shaped inner walls, the sloping surfaces of one ring engaging the adjacent sloping surfaces of the two opposed rings to form camming means responsive to relative endwise movements of the two tubular members for expanding and contracting alternate rings whereby said endwise movements are predeterminately resisted and cushioned.

9. A device connectible between two relatively movable bodies and being operative to adjust the position of one body relatively to the other and to resist and dampen undesirable movement between said bodies, the device returning said bodies to their normal relative positions after said undesirable movements cease, said device consisting of a housing connectible to one of said bodies, a reversible power device attached to said housing, a tubular member rotatably supported within the housing and operatively connected to the power device to be rotated thereby; another tubular member telescopically fitting into the first tubular member and keyed thereto to rotate therewith and move longitudinally relatively thereto, the contiguous annular surfaces of said tubular members, not provided with the key connection, being recessed to provide an annular chamber one end of which is substantially closed by adjacent abutment collars attached to the respective tubular members; a shaft slidably extending from the housing and attached to the other relatively movable body, said shaft extending into the said other tubular member and being threadedly connected thereto so that rotation of said other tubular member causes reciprocation of the shaft relatively to the housing; and a plurality of alternately engaging inner and outer metal rings on the inner and outer tubular members respectively, the respective end rings resting against the ends of the recesses in said tubular members and the abutment collars on said members, the engaging faces of the respective rings being wedge-shaped for effecting contraction and expansion of the respective inner and outer rings in response to relative endwise movements of said tubular members, which predeterminately resists and cushions said endwise movements.

10. A shock absorbing actuator consisting of a housing supporting a reversible power driven member; a tubular member rotatably supported in the housing and operatively engaged by the power driven member so as to be rotated thereby; a second tubular member within said first tubular member and keyed thereto so as to rotate therewith and be movable longitudinally relatively thereto; a non-rotatable shaft slidably supported by the housing and extending into said second tubular member to which it is operatively connected for longitudinal movement relatively thereto .in response to rotation of said second tubular member, and two groups of engaging elastic camming rings, each -wedge-'shaped= in cross-section one group supportedwithin the* first mentioned tubular member the second group supported upon the second tuloularmember; adjacent rings of said one gr-oup encompassing and engaging a ring'ofthe second group, said rings resisting deformation in response to longitudinal relative movements between said tubular members in accordance with the expansion and contraction qualities of the respective rings;

11. A device connectible 'between two relatively movable bodies for cushioning the movement of one of said bodies relatively to the other and for adjusting said one body relatively "to the other, said devices consisting of 'apowerrotated driving mechanism having two eline'ntsrotatable together but moi/mile longitudinally one 'rel' atively to the other, interengaging elastic means l2 interposedbet'w'een said elements normally resisting relative longitudinal movement therebetween, said means gradually yielding to a predetermined force applied longitudinally of either element for deforming said means and therebyv cushioning relative longitudinal movement between said elements; and a driven element operatively connected to one of the elements of 'the driving mechanism,=.said driven element moving longitudinally of said driving element in response 10 to rotation of the driving mechanism.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2538?,800 Leland etal Oct. 30, 1945 2,452,428 Bryant Oct. 26, 1948 Jan'eway etal Nov. 13,1951 

